Image Sequence to Movie - How to Get Desired Frame Rate?
I can't say for sure but the first thing I'd do is just render it out as an mp4 from Blender.
Here's a complete breakdown of the steps:
When you first open Blender hit the Video Editing preset.

Go to Add -&gt; Image/Sequence.

Go to the folder containing your images and sort them by name so that they are in order going down the folder.  Hit A to select all and add them to the timeline.

You should see the timeline something like this, now, and be able to play back your sequence with the controls at the bottom.
Note:  Playback will stutter because Blender does not prefetch the frames by default.  If you play it through a couple of times everything will be loaded in RAM, provided you do not run low, and it will play normally.

Now head over to the top right panel and make sure your resolution, frame start and end, and frame rate are what they should be.

Finally, scroll down to the Output section.  Pick a directory and change the file format to ffmpeg (or your choice).
And set the container and codec you want to use.